scottsm

This plugin provides a small randomly assembled monster avatar for each user based on their email address. Think gravatar only without requiring any external site and with monsters. Now with monsters consistent across servers. Based on idea and images by <a href="http://www.splitbrain.org/blog/2007-01/20_monsterid_as_gravatar_fallback" rel="nofollow ugc">Andreas Gohr</a> and artwork by <a href="http://rocketworm.com/" rel="nofollow ugc">Lemm</a>. See the plugin website if you need any help or for an example of the plugin in action.

WP_MonsterID

Creates a unique, persistent monster avatar for each commenter based on email address.

darkwolf74

Use <a href="http://dramatar.com" rel="nofollow ugc">Dramatar</a> generated avatars as your Default Avatar and get dramatic!
Dramatars are a new style of Avatars that come in several flavors. From Spirographs to the Abstract, plus fun avatars like Ragdolls.
This plugin adds a new default Avatar style for your blog discussions and works right along side of Gravatar for those who wish to display those idea for users who have Gravatar accounts. But, you can also just display our avatars. it’s up to you! There’s no coding or theme changes required, just activate and configure and you’re done.
For more information visit <a href="http://dramatar.com" rel="nofollow ugc">http://dramatar.com</a>

WP_MonsterID vs Dramatar